<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
    <title>Disabled button text color</title>
    <style type="text/css">
        body {
            font: 14px/1.2 Arial, Helvetica, sans-serif;
            padding: 30px;
        }
        fieldset {
            border: none;
        }
        input[type="button"] {
            height: 50px;
            padding: 0 20px;
            font-size: 2em;
            background: #519524;
            color: #FFFFFF;
            border: none;
        }
        input[type="button"][disabled] {
            color: #FFFFFF;
            opacity: 0.5;
        }
    </style>
</head>
<body>
    <form action="">
        <fieldset>
            <label>
                <input type="button" name="check" value="check" disabled="disabled" />
            </label>
        </fieldset>
    </form>
</body>
</html>